The present invention relates generally to computed tomography (CT) imaging techniques; and more particularly, to the backprojection of the attenuation data acquired during a scan to form an image.
In a computed tomography system, an x-ray source projects a cone beam that passes through an object being imaged, such as a medical patient, and impinges upon a two dimensional (2D) array of radiation detectors. The intensity of the transmitted radiation is dependent upon the attenuation of the x-ray beam by the object and each detector produces a separate electrical signal that is a measurement of the beam attenuation. The attenuation measurements from all the detectors are acquired separately to produce a transmission profile.
U.S. Pat. No. 5,446,776 describes a technique employing a conventional CT system employing cone beam geometry for 3D imaging using a cone beam x-ray source and a 2D area detector. The source and detector array in the system are rotated on a gantry preferably over a 360.degree. angular range, either by moving the cone beam x-ray source in a scanning circle about the object while keeping the 2D array detector fixed with reference to the cone beam x-ray source, or by rotating the object while the x-ray source and detector remain stationary. A group of x-ray attenuation measurements obtained from the detector array at a given angle is referred to as a "view". A "scan" of the object comprises a set of views made at different angular orientations during one revolution of the x-ray source and detector.
Different data processing techniques have been employed to present imaging data in manners that are helpful to the user e.g., providing tomographic information and the lie. Typically such processing, particularly for generation of 3 dimensional (3D) images, is computationally intensive, resulting in slow response due to lengthy processing time or requiring significant computational resources, with attendant cost, or both.